FDR,
thanks for your post
here but you remind me that I should not have left school that early .... For sure that luizmonteiro link is going straight to my favorites.
What I can say regarding AF447 and the relation between AoA and Indicated Airspeed is that the AoA will vary only marginally for a variation of speed between MMO and VLS.
I mention AoA but I could say Pitch as both match for a A330 in clean configuration for a level flight.
As put by HN39 earlier, maintaining green dot speed which is below usual cruising speeds, will produce a pitch attitude anywhere between 3.5 and 4 degrees. Green dot speed is not that far above VLS, so anything close to 5 degrees already, must be considered very seriously.
In case of erroneous airspeed indication, the crew will not necessarily notice such a minimal variation of pitch on their PFD. And I refrain mentioning turbulence ...
These unreliable airspeed indications at usual cruising flight levels can be a real trap for a crew, especially when the erroneous indicated airspeed is not recognised as such by the system, crew included.
Then you can also take account of the "protections" that may play around, but on the base of erroneous data …
